Discussion in 'Handloading and Reloading' started by 73ch13, Aug 21, 2016.
This is really getting off topic from the question about primer sealant but we shall see what we get.
Case: .308 Winchester RP Manufacture New.
Primer Pocket Diameter: 0.208".
Case Measured Head to Datum: 1.628" after sizing. About -0.002" of Nominal.
Case Length: Trimmed to 2.005"
Case: .223 Remington Win Manufacture New
Primer Pocket Diameter: 0.173"
Case Measured Head to Datum: 1.461" after sizing. About -0.003" of Nominal.
Case Length: Trimmed to 1.750"
The cases before being manually primed:
Primers and Primed cases. I used CCI Magnum primers on both calibers. The seated primers were seated till they bottomed out placing them right around 0.003" below the case heads. The CCI-250 Large Rifle had a diameter of 0.210" and the CCI-200 Small Rifle measured a 0.174" diameter.
The rifles used were both Remington 700 bolt gun variations. The chamber head space on these rifles are right around 1.632" for the .308 gun and 1.4655 for the .223 gun. Headspace as measured using Forrester chamber gauges of known accuracy.
Here is what the spent primers looked like after firing in an unobstructed barrel. They did try to back out a little finishing as flush with the case heads. If we look closely at the single primer images there is some shiny bright metal. This is where the primers backed into the bolt face stopping flush with the case heads. Look around 2 O'Clock on the .308 case.
Following firing of the primers the case sizes did not change. The cases as measured from case head to shoulder datum were the same for all five of each caliber. The .308 Winchester went in as 1.628" and came out as 1.628" and the .223 Remington cases went in at 1.461" and came out as 1.461" so nothing case dimensional wise changed. With the chamber heads paces I posted and the case dimensions posted while there was room for change there was no change. Additionally the case lengths remained the same also.
I did remove the bolts from both rifles prior to firing the primers and both extractors firmly grasped the case heads so when chambered in the rifles the case heads should have been flush on the bolt faces. Primer protrusion on both rifles is right around 0.060" and as can be seen both rifles made good deep primer strikes.
While absolutely none of this has anything to do with primer sealants it did make for an entertaining part of my afternoon.
I would start to suspect that his other knowledge might not be that good to rely on either...
LocTite won't help with primers.
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LMAO, I was wondering if anyone would catch that. Very observant of you.
How long have I had them? They are a mid 90s vintage so likely around 20 years. I still have boxes of 5,000 of the BR-2 and BR-4 bench rest CCI primers I was selling for $75 for 5,000. So anyway, roughly 20 plus years. All my primers were always stored in a cool dry place and after 20 years they all shoot great.
A friend recently used fingernail polish for the purpose to get just one more match out of expensive but overloaded Lapua brass.
That's just Silly.
If those case's rims are stopping against the extractor claw from firing pin impact, that's gonna cause accuracy problems.
There has to be enough clearance between bolt face and claw to let the case shoulder stop against the chamber shoulder centering the neck and bullet on the bore axis. Otherwise, the case neck and bullet are off bore center when the round fires; the rounds are tipped crooked in the chamber by the firing pin and pivoting where their rim is against the extractor claw.
If new case head space after sizing shortened .002", that may be part of the problem. What are both chambers' actual head space?
The exact headspace on each rifle is as follows:
The .308 Winchester comes in at 1.632". I have an eight gauge set of Forrester gauges for .308 ranging in 0.001" increments from 1.630" to 1.638" I can't close the bolt on the 1.632" but get a tight close on the 1.631".
The .223 Remington comes in at 1.4655". I used a Forrester Go gauge of 1.464" and added a small round piece of 0.002 precision stainless shim stock with the gauge making the bolt hard to close and could not quite close the bolt. So both rifles are right about 0.002" over the nominal of 1.630" for the .308 Winchester and 1.466" for the .223 Remington. I know my gauges are accurate, in fact very accurate. I retired from the Naval Reactors program and before retiring had all my gauges checked by my mechanical standards lab guys on a Zeiss CMM.
So if we muddle through the numbers I started with brand new cases. I decided to full length resize them. I ran them both using RCBS sizing dies, just the standard dies. My .308 dies can be finicky in that for a good full length resize I need only run the sizing die down to the shell holder and that typically yields 1.630" .308 brass. I may have advanced the die down a small bit when I snugged it. Thus I ended up with 1.628" cases. The rifle does shoot very well. This summer my best groups using AA 2495 were 0.4" at the hundred using SMK 168 gn bullets.
Both of the rifles I used to pop the primers shoot fine, the .223 gun likes the light bullets having a 1:12 twist. When chambering rounds the extractor claws grab the case rims as if I just chamber a round and then open the bolt I drag my loaded rounds out of the chamber.
Bart, my only surprise here is the cases came out exactly as they went in. The primers all popped just fine. They did try and back up but as I noted they look to have stopped at the bolt face. The shiny spots on the primers are likely from the bolt face.
We are really side tracking this poor thread. I apologize for that.
Bart, I haven't a clue as to biggest as I try for smallest. Even on a bad day it's me and not the rifle. Both rifles are 20 plus years old but have light use. I started shooting them more this year. There really is no largest groups as on a bad day I may shoot 1.5" groups at the hundred but when a rifle shoots 0.4" groups on Wednesday and the same rifle shoots 1.5" or 2.0" groups on Thursday under the same identical conditions it sure as heck is not the rifle. I simply do not keep track of biggest groups. I also don't save those targets.
As did I. Much appreciated.
Now I understand.
Thousands feel the same way.
Closely matches the probability spread a single 3- or 5-shot group of 1 inch has for 19 out of 20 of them shot from a benched rifle.
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